Alloy steel and method of making



Reissued June 22, 1937 ALLOY STEEL AND METHOD or MAKIN SAME Peter Payson, New York, N. Y., assignor to Crucible Steel Company of America, New York, N. Y., a corporation of New Jersey No Drawing. Original No. 2,009,914: dated July -30, 1935, Serial No. 6,645, February 15, 1935.

Application 91,993 21 Claims.

My invention resides in the discovery of a new .steel and in a methodior hardening'the same.

The .new steel is hardenable by said method up to C 65 Rockwell or more; it does not suffer any substantial permanent reduction in hardness after heating as high as 1400 or 1600" R, or in some instances to even higher temperatures; and thereby distinguishes from all known steels of which I am aware.

In addition, the new steel possessesa degree of hardness at temperatures of 1100 to 1800 F. or higher, which is superior to that'ci all known steels. The new steel is, moreover, resistant to corrosion, oxidation and scaling at elevated temperatures. It is, accordingly, exceptionally well adapted for such uses as valves and valve seats for internal combustion engines, hot -work.dies, die casting dies, high speed and other cutting, shearing, and forming tools, and the like.

Of the known steels, the austenitic' chromenickel alloys with or without additions of molybdenum, tungsten, titanium vanadium, silicon, etc., will retain their initial hardness when tempered up to 1600 F., but such steels are incapable of high hardness comparable to that of the steels of myinvention, The available normally ferritic, steels hardened in accordance with recognized practices, temper or soften when reheated after hardening. Although certain of these steels may -be so hardened initially as to be susceptible to V a slight carbide precipitation hardening at some retempering temperature up to about 1100 F.,

' they soften rapidly as the temperature is increased above 1100 F.

I have discovered, however, that certain ferrochrome alloys containing nickel-like metal, such a as either or both of nickel and manganese, and

containing molybdenum-like metal, such as either or both of molybdenum and-tungstem'in a propriate proportions, are susceptible to hardening by heating, with the resulting advantages and to the degree of hardness characterizing my invention as aforesaid.- I Steel conforming to the invention may be produced for example by alloying about 18% to 35% chromium, about 1% to 10% nickel-like metal, a about 1% to 10% molybdenum-dike metal, with term-metal, and heating within the approximate temperaturerange of 1200? 120-1800 I". for an for reissue'July 22, 1936, Serial No.

(01. Ila-21.5)

interval required to secure a desired hardening. The resulting hardness of the new steel is substantially unaffected by the rate of cooling.

The new steel may contain carbon in amounts ranging from the lowest percentages found in 5 commercial steels, for example .03% ,up to about 1.0%.

The alloying ingredients are preferably combined in such relative proportions as to render the steel initially ferritic, and-by initially fer- I title" I mean ferritic in the .as annealed, as I cast, as rolled, or as forged" condition.

It will be understood that it isthe treatment by adding chromium, molybdenum-like metal and nickel-like metal in the proportions stated and the heat hardening, which distinguish the steel of my' invention andthe process of treating the Steel conforming to the information above set forth may be readily rolled or forged into any of the usual shapes imparted to iron or steel, 35 and is likewise useful in cast form.

The degree of hardness acquired by the new steel in consequence of the heat hardening depends in part on the particular composition as well as on the prehardened condition, on the hardening temperature employed, and on the duration of heating, in the manner indicated by Tables I to IX, inclusive, presented and referred to hereinafter. y

The heat hardening may be accompanied by a marked reduction in magnetic permeability of the L steel, and hence presumably, by some phase change from an initially ferritie to a substantially non-ferritic state, as is evidenced by: 50

317m of heat treatment on hardness and mau Ifor magnetizing force of 300 oersteds.

These data show that heating above the hardening range of about 1200 to 1800, results in restoration of the initial order of magnitude of permeabiiity: thereby indicating a reversion of the steel from a non-ferritic to a ferritic condition.

The hardness of heat hardenedsteel in accordance with this invention is, as stated, substantially u'naflected by subsequent reheatings to temperatures up to 1400 or 1600? 'F. or even higher for some and this irrespective of the num-.

ening from the condition.

from: g e V Tana: III

Eflect on. hordenobllitv o1 prehardening condition [Steel =-;o-m\c,- sass Ni, 21.05 o 1.25 Is] Other factors remaining constant, maximumhardness is secured for steels having a carbon content below approximately 1.0%, but the hard ness isincreased progressively by additions of chromium, manganese, molybdenumor tungsten within the limits specified as is shown by Tables IV to D! inclusive, as follows: v

Tam IV 7 I have also found that hardening of the'new steel is a function of time at temperature, andis more readily secured and to an increased de-- gree if the steel is in the as forged? or as rolled" 7 condition before hardening, as compared to hardtempering tempera- 3o Eflect of carbon on hardenabilitn Cr constant at 24. or constant it 21. Ni constant at 5. Ni constant at 6. Mo constant at 8. a Mo constant at 4.5 o

' Hll'dnell, Rockwell "o" Hardness, amen "o" c I c Annealed Mm Anlllfled v Hardened .01 max. 18 88 .07 25 54 o .1o/.1s 1o 42 .10/.15 24 as .m ss 24 34 k .20/.2s 24 s1 hso ss as as .so .ss 2s 41 i ber. duration or temperature of individual heats, as appears from: a Tun: II

A Eardneu-Rockwell "0" Type oisteei percentage I 0- A! hudmad Hardness after reheating giglirat indicated by heating 1400 r. Or Ni 4 Mo 000 s00 1000 i200 1400 moo 1soo- 27.0' as as so so so so 21.0 5.0 1.1: as as as as g 32 24.0 so 4.5 40 4o 4o 40 4o 4o 40 21.0 5.0 4.5 47 41 41 41 41 41 41 so no so 7.s so so no so so co 'co so "In contrast to this performance. known steels of Turn V Eject of Or on hardenability c constant a .1o/.1s% Ni constant at 5.0% Mo constant at 4.5% s

so e .A comparison of the results in Tables VI and VII 'rm v1 Eflect of Ni on hardenability 1 constant at .1o/.1s% o constant at 401.15%

Cr constant at 21.07 0: constant at 27.0%

Mo constant at 1.5 n n Mo constant at 4.5%

f HsrdnesaltockwelWG" HardnesstRockwclWC U Annealed Hardened Annealed Hardened 2.5 14 21 2.5 19 43 5.0 is 44 5.0 24 55 7.5 is 45 7.5 25 53 Turn VII and molybdenum, or their equitfaients, are more Effect of Mn on hardenability C constant at max. Cr constant at 27.0% Mo constant at 4.5%

.Hardness, Rockwell O lVln Annealed Hardened shows that as regards its effect on hardenability, manganese may be substituted in whole or in part for nickel;

resistant than are the known steels to many acids and other corroding media, and are, moreover, highly resistant to oxidation and scaling at elevated temperatures.

In the appended claims by the term nickellike metal, I mean to include either or both of nickel and manganese; by the term molybde-.

num-like meta I mean to include either or both of molybdenum and tungsten; and by the term balance substantially all iron" I mean to include iron and steel containing commercial impurities.

What is claimed is:

1. An alloy steel containing: about 18% to 35% chromium, about 1% to 10% nickel-like metal, about 1% to 10% molybdenum-like metal, carbon up to about 1.0%, and the balance substantially all iron, in proportions to render said steel Turn VIII v \Eflect of Mo on hardencbility 0 constant at .l0l.l5% 0 oonstant at 401.15% 0r constant at 27.0% 01' constant at 27.0% Niconstantat 2.5% Ni constant at 5.0%

, Hardness, Rockwell "C" Hardness, Rockwell Q Mo Mo .Annealed Hardened Annealed Hardened 1.5 14 21 1.5 1s 44 3.0 17 a1 3.0 2o 51 4.5 19 4a 4.5 24 '55 0.0 '20 55 1.5 27 e0 Tam-.1 IX initially ferritic, said steel being hardened by heating within the approximate temperature E17 eat W hardemwit range of 1200 to 1800 F.

pconmntat 1017mm 2. An alloy steel containing: about 18% to c0n5t3ni3t27:0% 35% ohm ium, about 1% to 10% nickel-like N1 9 P metal, about 1% to 10% molybdenum-like metal,

1 carbon up to about 1.0%, and the balance sub- Hardness, Rwkwelwo stantially all iron in proportions to render said W I steel initially ferritic, said steel being hardened Annealed Hardened by heating within the approximate temperature range of 1200 to 1800 F., and developing its 10 1g maximum. hardness after heating within said ,0 1 range. 46 3. An alloy steel containing: about 18% to A comparison of the results in Tables VIII and IX shows that as regards its effect on hardenabillty, tungsten may be substituted in whole or in part for molybdenum.

. 35% chromium, about 1% to 10% nickel-like substantial reductionin hardness after heating as high as about 1400" F.

4. An alloy steel containing: about 18% to by heating within the approximate temperature range of 1200" to 1800" F.,and undergoing no substantial reduction in hardness after heating as high as about 1800 F.

5. An alloy steel containing: about 18% to 35% chromium, about 1% to 10% nickel, about 1% to 10% molybdenum, carbon up to about 1.0%, and the balance substantially all iron inproportions to render said steel initially ierritic, said steel being hardened by heating within the approximate temperature range of 1200 to 1800" F.

8. An alloy steel containing: about 18% to 35% chromium, about 1% to 10% manganese,- about 1% to 10% molybdenum,.carbon up to about l.0%,-and the balance substantially all iron in proportions to render saidsteel initially ien'itic, said steel being hardened'by heating within theapproximate temperature range of 1200 to 1800 F.

7-. An alloy steel containing: about 18% to 35% chromium, about 1% to 10% nickel, about 1% to 10% tungsten, carbon up to about 1.0%, and the balance substantially all iron in proportions to render said steel initially ferritic, said steel being hardened by heating within the approximate temperature range of l200 tov1800 F.

B. An alloy steel containing: about 18% to, 35% chromium, about 1% to-10% manganese, about 1%-to 10% tungsten,carb on up to about 1.0%, and the balance substantially all iron in proportions to render said steel initially ferritic, said steel being hardened by heating within the approximate temperature range of 1200 to all iron in proportions to render said steel initial-.,

ly ierritic, said method comprising: heating said alloy within the approximate temperature range ,o'i 1200 to 1800 F. to harden.

- iagx he method of producing a heat hardened 7 alloy st'eel consisting of about 18% to 35% chrornium, about 1% to 10% nickel-like metal, about 0..10% molybdenum-like metal, and carbon note about 1.0%. and the balance substantially all iron in proportions to' render said steel initially Ierritic, said method comprising: heating, said steel within the approximate temperature range 1200' to 1800" F. for an interval required to secure substantially maximum hardening 01' said steel.

11. Anarticle made of a heat hardenable alloy steel, resistant to corrosion, oxidation and sealing, and containing: about 18% to 35% chromium, about 1% to 10% nickel-like metal, about 1% to 10% molybdenum-like metal, carbon up to about 1.0% and the balance substantially all iron inproporti'on to render said steel initially ierritic, said steel being hardened by heating within the approximate temperature range oi 1200 to lame F 12. An article made of a heat hardenable alloy ierritic, said steel being hardened by heating within the approximate temperature range of I 1200 to 1800 F., and undergoing no substantial reduction in hardness after heating as high as within the approximate temperature range of 1200 to 1800'F., and undergoing no substantial reduction in hardness after heating as high as about 1800 F.

14. An alloy steel containing: about 18 to 35%.chromii1m, about lto 10% nickel-like metal, and about 1 to 10% molybdenum-like metal in proportions to render said steel -initially .ferritic,

characterized in being-hardened by heating said steel and holding within the approximate temperature-range of 1200 to 1800" F. until hardened, and in thereafter undergoing no substantial reduction in hardness after heating to temperatures as high as about 1400 F. I

15. An alloy steel. containing: about 18 to 35% chromium, about 1 to 10% nickel-like metal, and about 1 to 10% molybdenum-like metal in proportions to render said steel initially ferritic, characterized in being hardened inexcess of C 32 Rockwell by heating said steel and holding within the approximate temperature range of 1200 to 1800 F; until hardened, and in thereafter undergoing no substantial reduction in hardness after heating to temperatures as high as about 1400 F.

16. An article made of an alloy steel according;

to-claim 14.

17. A valve or valve element for internal combustion engines made of an alloy steel according to claim 14. I a

18. A cutting, forming or shearing tool made of analloy steel according to claim- 14;

'19. An article for use in the temperature range of about 1200 to 1800 F., made 01 an alloy steel according toclaim 14.

20. The method of producing a heat hardened alloy steel containing about 18 to 35% chromium,

prises, heating said steel and holdingwithin the approximate temperature range of 1200 to 1800 F. until hardened, and thereafter cooling saidsteel.

21. An alloy steel containing: about 18 to 35% chromium, about '1 to 10% nickel-like metal, and about 1 to'10% molybdenum-like metal, in proportions to render said steel initially ferritic, characterized in'being hardened by heating said steel and holding within the'approximate temperature range of 1200 to 1800 F. until hardened, the resulting hardness of said steel being substantially independent of the rate oi. cooling and undengoing no substantial reduction in hardness after heating to temperatures as high as about 1400" F.

PAYSON. j 

